This research has as a major objective investigation of the mechanism of initiation of chromosome replication. A lambda phage carrying the E. coli origin of replication will be used for studies on the role of a variety of factors necessary for initiaton including the dnaA gene product. In addition, the same bacteriophage will be used to study interactions between origin DNA and the cell membrane. A second objective is to study the mode of replication of bacteriophage Mu both in vivo and in vitro using small plasmids in which Mu DNA is integrated.